Comparative Efficacy of N95, Surgical, Medical, and Non-Medical Facemasks in Protection of Respiratory Virus Infection: A Living Systematic Review and Network Meta-Analysis

Background:  Current facemask guidelines for respiratory viruses vary, impeding policymakers and the general population in determining which facemasks are effective as personal protective equipment (PPE). We aimed to evaluate the comparative efficacy of N95, surgical/medical, and non-medical facemasks in preventing respiratory virus infection. Methods: This living systematic review and network meta-analysis (NMA) incorporated 31 published and unpublished randomised controlled trials (RCTs) and observational studies investigating specific mask efficacy against influenza virus, SARS-CoV-1, MERS-CoV, and SARS-CoV-2. We searched PubMed, Google Scholar, and medRxiv databases for studies published up to 22 October 2020 (PROSPERO registration: CRD42020214729). The primary outcome of interest was the rate of respiratory viral infection. Findings: N95 or equivalent masks were the most effective in conferring protection against coronavirus infections (RR, 0.37; 95% CI, 0.24–0.55; p < 0.001) consistently across subgroup analyses of causative viruses (SARS-CoV-1/MERS-CoV versus SARS-CoV-2) and clinical settings (community setting versus healthcare setting). There was a consistent trend towards reduced coronavirus and influenza infection rates with surgical or medical facemasks, albeit without reaching statistical significance; surgical or medical masks may show effect but lack in statistical power at this stage to detect a difference. Interpretation: Our study confirmed that the use of facemasks provides protection against respiratory viral infections in general; however, the efficacies may vary according to the type of facemask used. Our findings encourage the use of N95 respirators or their equivalents (e.g., FFP2 and KN95) in both community and healthcare settings. Funding: There was no funding source for this study. Declaration of Interests: We declare no competing interests.